1. Field of the Invention
The present invention relates to an antenna, and more particularly, to a broadband circularly polarized antenna using a radiator disposed between a metasurface and a ground plane.
2. Discussion of Related Art
Generally, antennas, which are conducting wires installed in the air in order to efficiently radiate electric waves to spaces or efficiently maintain electromotive force by the electric waves, are apparatuses which transmit and receive electromagnetic waves to and from a space for transmission and reception in order to achieve communication purposes in wireless communication.
Currently, a microstrip patch antenna of the antennas is being widely used in wireless communication systems due to its advantages such as a small size, high efficiency, broadband, multi-band, a specific radiation pattern, ease of manufacture and integration, low cost and the like.
The antenna requires a circular polarization characteristic rather than a linear polarization in many applications. This is because of advantages such as a strong circular polarization in a communication environment concerning polarization distortion, which is caused by radio interference in space and Faraday rotation, and a mitigated multipath fading compared to the linear polarization.
In order to achieve the circular polarization characteristic, a single feed circular polarization microstrip patch antenna has entered the spotlight. However, there is a disadvantage in that a bandwidth is small, less than 5%, in impedance matching and an axial ratio.
Conventionally, in order to increase the bandwidth of the single feed circular polarization microstrip patch antenna, attempts using a thick substrate, an L-shaped strip feed, loaded shorting pins, a stacked patch structure, and the like have been made. However, in most of the structures, there was a problem that an antenna height requires 0.1λo or a greater level.
Recently, in order to improve the performance of the antenna, such as size reduction, bandwidth expansion, and the like, research on a circularly polarized patch antenna using a metamaterial is being actively conducted. However, a circularly polarized antenna using a metamaterial while simultaneously satisfying a low antenna height and a bandwidth at an appropriate level or more has not yet been developed.